Note: This post (and the underlying report) was updated in October 2023 after additional research and analysis.
Summary:
- We find that advocacy for top sodium control policies to control hypertension to be highly-cost effective (~36,620 DALYs per USD 100,000, which is at least 10x as cost-effective as giving to a GiveWell top charity).
- Beyond raw cost-effectiveness estimates (which are highly uncertain), the cause looks highly promising, given the high quality of evidence underlying the theory of change.
- Reinforcing this, the expert consensus supports the fact that this is an effective solution for a growing problem.
- Further support comes from the fact the harder-to-quantify downsides to the intervention (e.g. lower freedom of choice) are comparatively low.
Our detailed cost-effectiveness analysis can be found here, as can the full report can be read here.
- Introduction: This report on hypertension is the culmination of three iterative rounds of research: (i) an initial shallow research round involving 1 week of desktop research; (ii) a subsequent intermediate research round involving 2 weeks of desktop research and expert interviews; and (iii) a final deep research round involving 3 weeks of desktop research, expert interviews, and the commissioning of surveys and quantitative modelling. Note also that an initial version of this report was published in July 2023, before being updated with further research in October 2023.
- Importance: Globally, hypertension is certainly a problem, and causes a significant health burden of 248 million disability-adjusted life years (DALYs) in 2024, as well as an accompanying net economic burden equivalent to 748 million foregone doublings of GDP per capita, each of which people typically value at around 1/5th of a year of healthy life. And the problem is only expected to grow between 2024 and 2100, as a result of factors like high sodium consumption, ageing, and population growth.
- Neglectedness: Government policy is far from adequate, with only 4% of countries currently implementing the top WHO-recommended ideas on sodium reduction, and this not expected to change much going forward – based on the historical track record, any individual country has only a 1% chance per annum of introducing such policies. At the same time, while there are NGOs working on hypertension and sodium reduction (e.g. in China, India and Latin America) – and while some are impact-oriented in focusing on poorer countries where the disease is growing far more rapidly than in wealthier countries – fundamentally, not enough is being done.
- Tractability: There are many potential solutions to the problem of hypertension (e.g. reducing dietary sodium, increasing potassium consumption, and pharmacological agents); however, we find that the most cost-effective solution is likely to be advocacy for top sodium reduction policies – specifically: a sodium tax; mandatory food reformulation; a strategic location intervention to change food availability in public institutions like hospitals, schools, workplaces and nursing homes; a public education campaign; and front-of-pack labelling. The theory of change behind this intervention package is as such:
- Step 1: Lobby a government to implement top sodium reduction policies.
- Step 2a: Sodium tax reduces sodium consumption.
- Step 2b: Mandatory food reformulation reduces sodium consumption.
- Step 2c: Strategic location intervention reduces sodium consumption.
- Step 2d: Public education reduces sodium consumption.
- Step 2e: Mandatory front-of-pack labelling reduces sodium consumption.
- Step 3: Lower sodium consumption in a single country reduces blood pressure and hence the global disease burden of hypertension
- Using the track record of past sodium control and sugar tax advocacy efforts and of general lobbying attempts (i.e. an "outside view"), and combining this with reasoning through the particulars of the case (i.e. an "inside view"), our best guess is that policy advocacy for top sodium reduction policies has a 6% chance of success. Meanwhile, based on various systematic reviews and meta-analyses, and after robust discounts and checks (e.g. for a conservative theoretical prior of a null hypothesis; for endogeneity; or for publication bias), we expect that top sodium reductions policies to significantly reduce sodium consumption: (a) sodium tax (-77 mg/person/day); (b) mandatory food reformulation (-226 mg/person/day); (c) strategic location intervention (-23 mg/day); (d) public education campaign (-35 mg/day); and (e) mandatory front-of-pack labelling (-53 mg/day). Finally, based on a quantitative model we commissioned an external expert epidemiologist – itself using parameters from meta-analyses and other empirical data – we expect that lower sodium consumption of 1mg/person/day in a single country will lead to a 0.000008% reduction in the global disease burden of hypertension.
- There are externalities to the top sodium reduction interventions – both positive, like a reduced disease burden of stomach cancer; or negative, like reduced freedom of choice as a result of a sodium tax. However, the impact of these externalities are marginal relative to the burden of hypertension itself (0.7% for stomach cancer) or low (-10% for freedom of choice). What is significant is the gain in cost-effectiveness (around 300%) from implementing the intervention in the most promising countries rather than the average one – that is, those countries suffering from some combination of a higher national disease burden, greater neglect by their governments and NGOs, and state fragility.
- Implementation Issues: From our interviews with NGOs working in the space, we find that there is a lack of funding; and this is backed up by observations from the academic literature. However, on the talent side of things, the NGOs we interviewed were more optimistic; they tended to believe that there is not a talent gap.
- Outstanding Uncertainties: There are a number of outstanding uncertainties, of which the three most important involve: (a) our use of point estimations (n.b. relying on them is reasonable given that we are ultimately interested in mean estimates, but caution is also warranted, as significant variance is possible); (b) the very simplified methodology we use to project the future disease burden of hypertension; and (c) the highly uncertain estimates of the probability of advocacy success.
- Conclusion: Overall, our view is that advocacy for top sodium reduction policies to control hypertension is an extremely cost-effective cause area, and we recommend that nonprofits, grantmakers, policy advocacy organizations, and indeed government themselves, implement the highly-impactful ideas detailed in this report.
Regarding increasing potassium intake:
A few weeks ago, I heard about this as a good idea via a podcast which claimed that getting closer to the potassium recommendations would remove a large part of the problems of high sodium consumption. I switched my salt to 2/3 sodium and 1/3 potassium a few weeks ago, and until now I didn't notice negative effects on taste[1].
Given that potassium is not that expensive, my impression was that a public policy of "everyone, potassium is x% part of table salt from now on" would lead to a large chunk of the benefits without people having to change their taste preferences a lot (by both decreasing sodium by x% and increasing potassium consumption correspondingly). This would increase the prize of salt significantly, which should have similar effects to a sodium tax (the prices would still amount to low single-digit cent costs per day even for high salt consumption).
I would be curious about your thoughts on this, given that you have researched this topic a lot more deeply :)
Nonetheless I could still imagine that there are a number of foods with completely excessive amounts of salt for which other interventions would still be a good idea.
I trust the nutritionist enough to be confident that this change is a good idea for me personally, but I did not look up the sources and I might well have misunderstood the effect-size of increasing potassium consumption ↩︎
Hi Mart,
Thanks for your interest! You would have seen the discussion of potassium in the section on potential interventions - and I think the TLDR is that it does look good, but does cost money. Hence, we're pursuing sodium reduction right now; but as we work with our partners doing the actual advocacy reach-out to governments, we'll definitely get them to raise potassium as an option. Hopefully, in the long term, economies of scale make these more cost-competitive.
That makes a lot of sense - in practice, there are many relevant considerations and other interventions might well be preferable in many contexts.
The expert opinion
also sounds as if potassium-enriched salt surely helps to some degree, but probably isn't a solution by itself. And I get the impression that research in the coming years will probably improve the uncertainties here.
Apart from this, I am a bit surprised that the costs ("perhaps double the price") would be a problem for richer countries. If I am understanding this right, this should still be obviously worth it as a health expenditure? A very simple estimate might be:
Of course this isn't comparable to GiveWell effectiveness, but it is really cheap compared to other health expenses.
The thing is that potassium salt (or mixed sodium/potassium salts) are available in rich country; it's really just a matter of uptake. Consumers might not know or think much about the health aspects of things; they might not be price sensitivity; and even "double" is an off the cuff estimate by the expert, and it probably depends on country and location (e.g. f I check Walmart's e-commerce website, Morton's potassium salt is 10x as expensive as normal salt).
So it goes back to policy, and whether governments should just regulate sodium content even in salt - we didn't really explore this, given the higher evidence base and cheapness of salt policies.
That makes a lot of sense!
This describes me quite well in many of my health choices, and unfortunately this is apparently really common.
In my case, I also did not find salt that is pre-mixed at a price that makes sense to me - I bought a pharma-grade bag of KCl and mixed it with usual table salt myself[1], which resulted in a net-price that is 3x of the usual sodium salt.
That sounds very reasonable - I'll be looking forward to hearing about updates in the future!
with the hope that diluting by 1/3 will not be too much for the anti-hygroscopic components of the store-bought table salt ↩︎
Wow thanks I didn't know about the potassium alternative ( and in as doctor), that's exciting I might look into it for myself!
Would not be a difficult cost effectiveness analysis to see if this made sense, nice idea.
I just realized that I could also just follow the links and found a part of the answer
in section 4.1 1) g)
and also
in section 3.3. Global Salt NGO, point 2.
I am happy to learn that people are working on this :) And it does make sense that the increased price also creates difficulties for adoption. This certainly isn't a trivial problem. Also, I agree that the public relations perspective is important. Here in Germany, there were large health problems due to missing Iodine, which were reduced by fortifying table salt - but even though the necessity for Iodine hasn't changed, people/products are starting to use the fortified salt less.
I really like this post.
I was just commenting on a post about the value of maintaining the umbrella organisation and label "Effective Altruism." This study is a perfect example of why it's important.
Thanks, Denis!
I think the main takeaway for other cause areas would probably just be how impactful changing government policy is - you trade off (a) needing to persuade governments in the first place, for (b) massive scale of impact and also (c) much, much lower counterfactual cost of government expenditure relative to EA expenditure. There's a lot of stuff that may not be worth doing if the price was less money to GiveWell; but not if the price was the US government running a slightly higher budget deficit.
Good perspective. Thanks for answering!
Also in support of the sodium tax is that we've seen health taxes used as a cost-effective way improve health/save lives in tobacco, alcohol, and sugar sweetened beverages. For tobacco, taxation is the most cost-effective of all the tobacco control measures. I'm not surprised to see the evidence point to a sodium tax.
Definitely - though I think mandatory reformulation is the best amongst the existing top solutions we recommend. It shows the largest effect size under the modelled parameters, but also it's probably less politically toxic - taxes are comparatively harder. We see this with climate too, where people favour quotas/quantitative limits over taxes even if the effects are literally identical.
Very nice summary, Joel. Please note that in addition to the SSASS cluster-randomized clinical trial https://www.nejm.org/doi/full/10.1056/nejmoa2105675, there has also been this more recent cluster-randomized potassium substitution trial: https://www.nature.com/articles/s41591-023-02286-8 & an older cluster-randomized potassium substitution trial https://www.sciencedirect.com/science/article/pii/S0002916523294599?via%3Dihub.
The final table in the Supplement is essential to understanding the conclusion of the above study published recently in Nature Medicine -- in summary sodium reduction per se didn't have an impact, but as best I can tell that could be because sodium reduction wasn't achieved at all.
This article by Derek Denton offers a great deal of useful information on this topic: https://www.nature.com/articles/1000489.